Alpha-alkyl, 4-alkyl cyclohexylbutyric acids



Patented July 10, 1951 UNITED STATES, PATENT OFFICE ALPHA-ALKYL,4-ALKYL, QYQLQHEXYL- BUTYRIC ACIDS:

Earl L. Pelton and Andrew A. Holzschuh, Midland, Mich., assignors, .to The Dow Chemical Mich, a corporation of Gompany, Midland, Delaware No Drawing. Application January 3, 1949,

This invention relatesfto certain new v-alkyl 2 Claims. 01. 250 1514.),

caproic acids and to certain 'Y,4-di-alkyl-2-cyclo hexene-l-caproic acids and a l-di-alkyl cyclohexanebutyric acids.

I e larer rat en i m diei ia s. and. ot er interesting compounds, including; plasticizers, it is Sometimes. desirab e. o use a a tartin ma ri l a branched chain aliphatic acidi' One class of such compounds which has. not been available anols. That process; consists, essentially in heating the substituted cyclohexanol with a fused alkali metal hydroxide, or mixture of such hydroxides, at temperatures in the range from 290 to 375 C., to effect oxidative scission of the ring, and recovering the resulting organic acids after acidification of the reaction mixture with a mineral acid.

The following examples will illustrate the meth- 0d of preparing the new acids:

Example 1 50 pounds of 90 per cent potassium hydroxide was mixed with -5 pounds of sodium acetate, to lower the viscosity of the mixture when molten, and was heated to 350 C. in a horizontal, nickellined cylindrical reaction vessel about '18 inches in diameter and 30 inches long. The vessel contained a horizontally disposed rotary shaft with nickel stirrer blades mounted thereon, and was provided with an inlet for the alkyl cyclohexanol and an outlet for hydrogen, steam or other gases and vapors. The latter outlet was connected with a water-cooled condenser. There was added to the fused caustic alkali in the course of 16 hours about 7 3 pounds of 4-tertiary butyl cyclohexanol, which had been melted in a steam-heated funnel. The reaction temperature was reduced to 300 C. and held for several hours. The reaction mixture was then cooled, dissolved in water, and acidified with hydrochloric acid. The organic compounds separated from the resulting brine and were dried and distilled. There was obtained 76 per cent of the theoretical yield of 'y-tertiary butyl caproic acid and a 4 per cent yield of aA-di-tertiarybutyl cyclohexanebutyric acid.

Example 2 In the apparatus described in Example 1, there was placed 50 pounds of an equimolar mixture of sodium and potassium hydroxides and 5 pounds of; sodium acetate. This mixture was fused and heated to 300"" 0., and 12 6' pounds of 4-tertiary butyl cyclohexanol was added over the course of 16 hours. Under these reaction conditions, using a lower fusion temperature, more of the alcohol entered into condensationv reactions, and there was obtained 97 pounds of an oily mixture of organic materia1 consisting of 1.5 per cent. low: boiling fraction 10.0 per centzyi -tertiarybutyl caproic acid 735 per cent aA-di-tertiary butyl cyclohexanebutyric acid 15.0 per cent dark brownresin I Example 3 When equal weights of potassium hydroxide and l-secondary butylcyclohexanol were heated together at 350 C., and the product recovered as before, there was obtained a 46.8 per cent yield of 'y-secondarybutyl caproic acid and a 19.5 per cent yield of aA-di-secondarybutyl cyclohexanebutyric acid, together with about 5 per cent of *yA-disecondarybutyl 2-cyclohexene-1-caproic acid.

Ezndmple 4 1000 parts by weight of 4-isopropyl cyclohexanol, 750 parts of potassium hydroxide and 100 parts of potassium acetate were caused to react in similar manner at 330 C. The product was recovered as before and, based on the amount of the alcohol used, the yields of the respective acids were:

14.2 per cent 'y-isopropyl caproic acid 13.1 per cent a,4-di-isopropyl cyclohexanebutyric acid 41.0 per cent 'yA-di-isopropyl 2-cyclohexene-lcaproic acid In a similar manner, numerous other 'y-alkyl caproic acids, a,4-di-alkyl cyclohexanebutyric acids, and 'yA-di-alkyl 2-cyclohexane-l-caproic acids are produced, having from 3 to =6 or more carbon atoms in the alkyl radical. The substituted butyric acids which are obtained by the described process are undoubtedly the result of the alkaline oxidation of previously formed caproic acid compounds, with two carbon atoms going to form sodium acetate. The alkyl caproic acids result directly from the oxidative scission of the original 4-alkyl cyclohexanols. The aA-di-alkyl cyclohexanebutyric acids and the 'yA-di-alkyl 2- cyclohexene-l-caproic acids are indications of the formation, as intermediates, of condensation products containing two alkylcyclohexyl groups, only one of which retains an alcoholic structure and is susceptible to further oxidative action of the hot alkali bath.

Among the new compounds of the present invention, the following are of especial interest:

4 which the alkyl groups are alike and have from 3 to 6 carbon atoms, inclusive.

Identifying Properties Name Reira tive Amide Physical M. P B. P., Density indgx M P 1 form O O./mm 25/4 C. CJD 6 -iSOPIODYI caproic acid liquid 129/10 0.9261 1. 4363 82. 3-83 seeondarybutyl caproic acid "do 139/10 0.92 1. 4405 59. 5-60. 5 mrtiarybutyl caproic acid do 140-2/10 918 (20) 1.4423 (20) 93.1-93.7 7, 4-di-isopropyl 2-cycloi1exene-1-caproic ac .do 207/ a, 4-di-isopropyl cyclohexane-butyric acid... do. 180-2/5 0. 9381 1. 4651 a, 4-di-secondarybutyl cyclohexanebutync acid ..i do. 192/3 0. 9820 1. 4702 a, 4-di-tertiarybutyl cyclohexanebutyric acid solid- 107. 5-108. 5

With exception of the last-named acid which is a white crystalline solid, all of the acids listed in the table are oily liquids, whose viscosity is roughly proportional to their molecular weights.

The new compounds, all obtainable by the fusion of 4-alky1 cyclohexanols with caustic alkalies, have the general formula wherein X is an alkyl-radical having from 3 to 6 carbon atoms, inclusive; n has one of the values 0 and 2; when n is 2, X is selected from the group consisting of hydrogen and the 4-a1ky1 2-cyclo- 2. aA-di-tertiarybutyl cyclohexanebutyric acid.

EARL L. PELTON. ANDREW A. HOLZSCHUH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 25 Number Name Date 1,961,623 Pelton June 5, 1934 2,130,989 Schimmelschmidt Sept. 20,1938

OTHER REFERENCES Burton et a1.: Beilstein (Handbuch, 4th ed), vol. '2, p. 350 (1920).

Adams et a1.: J. Am. Chem. Soc., vol. 49, pp. 2934-2940 (1927).

Advani et a1.: Beilstein (I-Iandbuch, 4th ed.,

1. An aA-di-alkyl cyclohexanebutyric acid, in d upp V 2,-p. 299 (1942). 

1. AN A,4-DI-ALKYL CYCLOHEXANEBUTYRIC ACID, IN WHICH THE ALKYL GROUPS ARE ALIKE AND HAVE FROM 3 TO 6 CARBON ATOMS, INCLUSIVE. 